U.S. Pat. No. 3,629,328 discloses a method of purifying organic acids such as terephthalic acid by forming a solution of the acid in an aqueous solution of a weak acid salt of magnesium, treating the solution to reduce impurities upon recrystallization of the acid, cooling the solution to recrystallize the acid in a free acid form, and separating the acid from the mother liquor.
U.S. Pat. No. 3,115,521 discloses a process for purifying aromatic acids by treating an aqueous solution of an alkaline salt of an aromatic carboxylic acid with carbon monoxide under pressure. The impurities precipitate, and the solution can be further treated with activated carbon to remove the remaining colored impurities.
U.S. Pat. No. 2,745,872 discloses a method for separating mixtures of salts of terephthalic acid and isophthalic acid by forming a mixture of the salts with a concentrated aqueous solution of an inorganic alkali metal salt, the aqueous solution being insufficient to dissolve all of the mixed alkali phthalic acid salts, and separating a solid phase and a liquid phase from the mixture.
U.S. Pat. No. 3,206,504 discloses a method for separating isophthalic acid from other aromatic carboxylic acids by treating the mixture of acids with reagents to preferentially solubilize the terephthalic acid and monocarboxylic acids present without solubilizing too much of the isophthalic acid, and then separating a solution of the solubilized impurities from the solid bulk of the mass.
Canadian Pat. No. 718,043, discloses a method for separating impurities from naphthalene dicarboxylic acid prepared by the oxidation of dimethylnaphthalene. Impure dinaphthalene carboxylic acid is dissolved in aqueous sodium hydroxide, acidifying the solution to precipitate impurities, separating the impurities, further acidifying the solution to precipitate purer naphthalene dicarboxylic acid and separating the acid.
Canadian Pat. No. 498,786 discloses a process for oxidizing coal at elevated temperature and pressure with an oxygen-containing gas in the presence of an aqueous alkaline solution to produce a solution of alkaline salts of organic acids such as sodium salts. The alkaline solution is then discharged from the reaction vessel and is filtered to remove ash. The alkaline solution is then treated with a mineral acid to free the organic acids from their salts. The organic acids in solution are extracted from the acidified aqueous solution by a solvent such as methyl ethyl ketone.
British Pat. No. 815,835 discloses a process for producing aromatic carboxylic acids, their esters and salts, by reacting an aromatic halogenated hydrocarbon with the formate of an alkali or alkaline earth metal at an elevated temperature or pressure. Instead of using formate directly, the formate may be formed in situ using a compound such as magnesium hydroxide. The reaction may then be extracted with benzene, and the residue treated with water and acidified. The precipitate is the free acid desired.
U.S. Pat. No. 2,785,198 discloses a process for producing polycarboxylic acids from bituminous coal, lignites, peat and the like or their carbonization products such as coal, tar, or pitch by thermal treatment with oxidizing agents such as nitric acid, chromic acid, permanganate, or oxygen or air under super-atmospheric pressure in an alkaline medium. The alkaline medium disclosed is sodium hydroxide. Also disclosed is a process for extracting low molecular weight polycarboxylic acids from the crude oxidation product produced by the thermal oxidation of carbonaceous matter. The oxidation produced is extracted with at least one polar organic solvent for both the monocyclic aromatic and the high molecular weight polycarboxylic acids so as to cause dissolution of the polycarboxylic acids. The solution is treated with water to dissolve the monocyclic acids in the water. The aqueous solution of monocyclic aromatic polycarboxylic acids is separated from the remainder of the mixture, and the monocyclic aromatic polycarboxylic acids are recovered.
The crude oxidation product is subject to an extraction treatment with a polar organic solvent for both the monocyclic aromatic and high molecular weight polycarboxylic acids, and treating the thusly formed solution with water to extract the monocyclic aromatic polycarboxylic acids from the remainder of the mixture.
U.S. Pat. No. 2,193,337 discloses a process for producing organic acids by heating carbonaceous material such as sawdust, wood chips, peat, or coal with oxygen-containing gases at elevated pressures and temperatures in the presence of at least 10 times the weight of the carbonaceous material of water and preferably an oxide or hydroxide of an alkali or alkaline earth metal. Oxalic acid and other organic acids which are formed, such as mellitic and benzoic acid or acetic acid, may be isolated from the resulting reaction mixture as salts of the alkali or alkaline earth metals. The caustic material disclosed is an oxide or hydroxide of an alkali metal or an alkaline earth metal and specifically lime, quick-lime, and caustic soda.
U.S. Pat. No. 2,786,074 discloses a process for making organic acids by oxidizing carbonaceous materials at elevated temperatures and pressures with gaseous oxygen in the presence of an alkaline solution. Alkalis which are suitable for use in a high pressure reactor are specified as sodium hydroxide, potassium hydroxide, and mixtures thereof.
U.S. Pat. No. 2,461,740 discloses a process for oxidizing carbonaceous material to aromatic acids using a two-stage oxidation process.
In the first stage, the carbonaceous material is oxidized to a state where it is soluble in aqueous alkali such, for example, as a solution of sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate, especially at elevated temperatures.
Any acid or acid anhydride with suitable oxidizing properties which can be regenerated by air and recycled in the process can be employed, for example, sulfur trioxide, oxides of nitrogen, or the acids formed by reaction of these compounds with water. Specifically disclosed are sulfur trioxide, N.sub.2 O.sub.3, and N.sub.2 O.sub.5.
In the second stage, U.S. Pat. No. 2,461,740 discloses the use of a high pressure elevated temperature reaction of oxygen gas in aqueous alkali. The aqueous alkali employed is a solution of sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate.
U.S. Pat. No. 3,023,217 discloses a process for introducing carboxyl groups into aromatic compounds free from carboxyl groups, such as aromatic carbocyclic hydrocarbons and aromatic heterocyclic hydrocarbons. The patent discloses a process for introducing into aromatic carbocyclic or aromatic heterocyclic compounds free from carboxyl groups by reacting such materials in the absence of substantial amounts of oxygen, such as a non-oxidative atmosphere and under anhydrous conditions, with alkali metal salts of aliphatic carboxylic acids at elevated temperatures and pressures in the presence of catalysts. As disclosed in the process, it is necessary to exclude the presence of substantial quantities of oxygen. Examples of aliphatic carboxylic acids which are used in the form of their alkali metal salts, especially their potassium salts, are oxalic acid, malonic acid, maleic acid, and trichloroacetic acid.
Examples of suitable compounds free from carboxyl groups which may be used as starting materials for the process are aromatic carbocyclic compounds free from carboxyl groups such as monocyclic aromatic hydrocarbons such as benzene or its derivatives having saturated alkyl or cycloalkyl substitutes attached thereto, and dicyclic aromatic hydrocarbons such as naphthalenes, diphenyl, and other polycyclic aromatic hydrocarbon compounds. Similarly, aromatic heterocyclic compounds free from carboxyl groups which may be used as starting materials are heterocyclic compounds which contain one or more heteroatoms in the ring and which are designated as having an aromatic character because of their chemical behavior.
U.S. Pat. No. 2,948,750 discloses a process for carboxylating aromatic hydrocarbons by direct introduction of carbon dioxide to produce polycarboxylic acids.
Suitable starting materials which are disclosed are aromatic hydrocarbons, especially benzene but also toluene, xylene, cumene and diisopropyl benzene and other benzenes substituted with saturated or unsaturated alkyl or cycloalkyl radicals, naphthalene, diphenyl, diphenylmethane and other aromatic compounds which may also be substituted with hydrocarbon radicals.
Selective carboxylation is accomplished by heating the starting materials in the presence of an acid-binding agent, and carbon dioxide under anhydrous conditions. Examples of the acid-binding agent are carbonates of alkali metals, especially potassium carbonate, the salts of other weak acids such as bicarbonates, formates, or oxalates. Similarly, the corresponding compounds of other metals are suitable; for example, the carbonates of the alkali earth metals.
U.S. Pat. No. 3,023,216 discloses a method of introducing carboxyl groups into aromatic carbocyclic compounds free from carboxyl groups by reacting these compounds in a non-oxidative atmosphere with alkali metal salts of aromatic carbocyclic or aromatic heterocyclic carboxylic acids.
Suitable compounds which are free from carboxyl groups which may be used as starting compounds in this patent are similar to the starting compounds in U.S. Pat. No. 2,948,750.
U.S. Pat. No. 3,023,216 discloses reacting aromatic carboxylic compounds free from carboxyl groups with aromatic carboxylic acids in the form of their alkali metal salts.
Both U.S. Pat. Nos. 3,023,216 and 2,948,750 require specific chemical compounds as starting materials.
U.S. Pat. No. 2,833,816 discloses a process for oxidizing aromatic compounds using a catalyst comprising a lower aliphatic carboxylate salt of a heavy metal and bromine. Examples of a heavy metal are manganese, cobalt, nickel, chromium, vanadium, molybdenum, tungsten, tin, and cerium.
The metals may be supplied in the form of metal salts; for example such as manganese acetate. The bromine may be supplied as ionic bromine, or other bromine compounds soluble in the reaction medium such as potassium bromate.
Thus, the process requires the conjoint presence of bromine and a heavy metal oxidation catalyst.
The starting material required is an aromatic compound containing one or more aliphatic substituents to produce corresponding aromatic carboxylic acids.
U.S. Pat. No. 3,064,043 discloses a process for oxidizing para-toluic acid or para-formyl toluene to produce terephthalic acid.
U.S. Pat. No. 3,064,046 discloses a process for oxidizing toluic acid or formyl toluene to produce orthophthalic acid or isophthalic acid.
Both U.S. Pat. Nos. 3,064,043 and 3,064,046 require specific starting materials to be oxidized.
U.S. Pat. No. 3,558,458 discloses a process for preparing aromatic acids by treating an alkyl aryl ketone with water at an elevated temperature in the presence of a reaction promoting agent. The reaction promoting agent may comprise an alkaline catalyst, a transition metal salt, or actinic light. Examples of an alkaline catalyst include potassium acetate, lithium acetate, rubidium acetate, and cesium acetate. The process is conducted in water at a temperature of about 200.degree. to 400.degree. C.
The art discloses processes for the alkaline oxidation of coal employing large amounts of chemicals relative to the amount of water soluble coal acid produced, see U.S. Pat. No. 2,786,074 and a report entitled "Production of Chemicals by Oxidation of Coal", Battelle Laboratory, Columbus, Ohio of Mar. 31, 1975.
Recovery of caustic soda and sodium carbonate was disclosed by Industrial and Engineering Chemistry, Volume 44 (1952), at page 2791 in an article entitled "Water-Soluble Polycarboxylic Acids by Oxidation of Coal" beginning at page 2784.
Japanese patent disclosure 18,365 discloses the reclamation of alkali by recrystallization and requires the consumption of one part by weight of the alkali and 1.5 parts of sulfuric acid for each two parts of coal consumed.
Non-alkaline oxidation of coal generally yields about 10 parts by weight of water soluble coal acids based on 100 parts of coal carbon consumed. Alkaline oxidation yields have been about 30 to about 42 parts per 100 parts of coal carbon consumed. Therefore, alkaline oxidation processes are favored because of the higher yield possible.
In systems like HCl/KCl, H.sub.2 SO.sub.4 /K.sub.2 SO.sub.4, and HNO.sub.3 /KNO.sub.3, the salts do not produce an alkali solution by hydrolysis because the acids involved are too strong. These systems over oxidize the coal and therefore result in much lower yield of coal acids.
Another disadvantage of treatment of coals with strong acids is the production of unwanted by-products by chlorination, sulfation, or nitration of the aromatic nuclei of the coal.
Coal acids have been prepared by nitric acid oxidation, U.S. Pat. Nos. 3,468,943; 3,709,931; 2,555,410; in the presence of nitrogen catalyst, U.S. Pat. No. 3,702,340; and oxidation in a non-alkaline aqueous medium, U.S. Pat. No. 3,259,650.
The caustic-oxygen treatment of coal has been described in U.S. Bureau of Mines Information Circular No. 8234 at pages 74 to 98.
In another process, U.S. Pat. No. 3,259,650 discloses the use of a non-alkaline medium and produces lower yields of water soluble coal acids.
U.S. Pat. No. 2,927,130 discloses a process for the recovery of alkalis and terephthalic acid from aqueous solutions containing alkali salts of terephthalic acid. Alkalis of interest are sodium, potassium and ammonium. The patent discloses that dialkali salts of terephthalic acid in aqueous solution can easily be divided into difficulty soluble monoalkali salts and alkali bicarbonate by introducing carbon dioxide into the solution, and that the difficulty soluble monoalkali salts of terephthalic acid can be hydrolyzed with water into free terephthalic acid and dialkali salts of terephthalic acid. The free terephthalic acid separates out as a solid, while the dialkali terephthalate remains in solution.
U.S. Pat. No. 2,819,300 discloses a process for oxidizing carbonaceous material with nitric acid, and then oxidizing the oxidation products produced from the nitric acid-carbonaceous material reaction with sulfuric acid to complete the oxidation to benzene carboxylic acids.
Although oxidation can be carried out in reclaimable acidic media, these processes are not as desirable because of lower yields and unwanted by-products due to chlorination, sulfation, and nitration.
The art discloses a process for preparing terephthalic acid by heating pure potassium phthalate, or pure potassium isophthalate, or pure potassium benzoate in the presence of catalyst such as cadmium, zinc and other metals, as reported in the Journal of American Chemical Society, Volume 79, pages 6005 to 6008.
The art discloses a catalytic process for preparing terephthalic acid from toluene by oxidizing toluene to benzoic acid, reacting the thusly formed benzoic acid with potassium terephthalate in a methathesis reaction to produce terephthalic acid and potassium benzoate, and heating the thusly formed potassium benzoate in the presence of a catalyst to produce potassium terephthalate and benzene by a disproportionation reaction. Terephthalic acid and benzene are recovered and the thus formed potassium terephthalate is recycled to the methathesis reaction. The process is reviewed in Stanford Research Institute Report No. PEP'76-2-3 of February, 1977.
U.S. Pat. No. 3,215,735 discloses a process for treating a solution containing dialkali terephthalate and non-terephthalic acid as impurities with a reagent to adjust the pH of the solution so that terephthalic acid is in a soluble form while essentially all of the non-terephthalic acid is in an insoluble filterable form.
U.S. Pat. No. 3,579,572 discloses a process for the production of terephthalic acid which comprises treating an aqueous lithium or magnesium terephthalate solution with carbon dioxide under pressure, at a temperature between its solidification temperature and 80.degree. C., and separating the terephthalic acid which precipitates.
U.S. Pat. No. 3,766,258 discloses a process for the catalytic carboxylation of an alkali metal aromatic carboxylate to an acid containing at least one more carboxyl group.
U.S. Pat. No. 2,171,871 discloses that alkali metal derivatives of organic acid salts may be reacted with various reagents reactive with alkali metal organic compounds, e.g. carbon dioxide, sulfur dioxide or organic halides, to produce valuable products.
U.S. Pat. No. 2,176,348 discloses a process for preparing mellitic acid by a two-step oxidation of coal. The coal is first treated with a suitable oxidizing acid with or without the presence of a catalyst, followed by oxidation with an oxidizing salt such as alkaline permanganate.
U.S. Pat. No. 2,762,840 discloses that polycarboxy aromatic acids can be prepared by controlled oxidation with oxygen gas of an aqueous, alkaline suspension of bituminous coal.
U.S. Pat. No. 2,981,751 is directed toward a process for the oxidation of substituted aromatic compounds having at least one aliphatic, cycloaliphatic or partially oxidized aliphatic or cycloaliphatic substituent attached to the aromatic nucleus in the presence of an oxygen-containing gas and a calcined solid oxidation catalyst.
The substituted aromatic feed materials disclosed are toluene, butylbenzene, xylene, cumene, durene, dibutylbenzene, acetophenone, propiophenone, benzaldehyde, tolualdehyde, Tetralin, para-xylene, acetophenone, and cumene hydroperoxide. The oxidation is in the presence of a calcined solid oxidation catalyst which is derived by calcining an inorganic base having deposited thereon catalytic amounts of a promoting metal component.
U.S. Pat. No. 3,529,020 discloses a process for oxidizing an organic material in the presence of a heavy metal crystalline aluminosilicate having uniform pores sufficiently large to permit entry of at least a portion of the organic material, and an oxidation initiator which is present in the pores. The heavy metal crystalline aluminosilicate acts as a catalyst.
One embodiment of this invention is a process for producing benzene carboxylic acid salts comprising treating a mixture of an aromatic material, water, a water soluble reagent comprising a Group Ia or IIa metal, the reagent producing an alkaline solution by hydrolysis, and a promoter agent, with oxygen under conditions sufficient to convert at least a portion of the aromatic material to a benzene carboxylic acid salt of the reagent. The promoter having the formula R--X--CH.sub.2 --R', wherein:
R comprises a radical selected from the group consisting of alkoxy, phenoxy, substituted phenoxy, hydroxyl, carboxyl, aldo, keto, phenyl, substituted phenyl, alkyl, substituted alkyl, and hydrogen; PA1 X comprises a radical, with at least two points of substitution, selected from the group consisting of benzene ring, substituted benzene ring, multi-ring system, substituted multi-ring system, saturated ring, substituted saturated ring, and (CH.sub.2).sub.n, where n is an integer of at least one; and PA1 R' comprises a radical selected from the group consisting of hydrogen, alkyl, substituted alkyl, phenyl, substituted phenyl, hydroxyl, carboxyl, aldo, keto, alkoxy, phenoxy, and substituted phenoxy. PA1 R comprises a radical selected from the group consisting of alkoxy, phenoxy, substituted phenoxy, hydroxyl, carboxyl, aldo, keto, phenyl, substituted phenyl, alkyl, substituted alkyl, and hydrogen; PA1 X comprises a radical, with at least two points of substitution, selected from the group consisting of benzene ring, substituted benzene ring, multi-ring system, substituted multi-ring system, saturated ring, substituted saturated ring, and (CH.sub.2).sub.n, where n is an integer of at least one; and PA1 R' comprises a radical selected from the group consisting of hydrogen, alkyl, substituted alkyl, phenyl, substituted phenyl, hydroxyl, carboxyl, aldo, keto, alkoxy, phenoxy, and substituted phenoxy.
The promoter also comprises at least one easily extractable hydrogen, and has the property of increasing the yield of benzene carboxylic acid salt thusly produced from said aromatic material by an amount higher than the conversion of the aromatic material to benzene carboxylic acid in the absence of said promoter.
In another embodiment the promoter agent has the property of increasing the yield of benzene carboxylic acid salts by an amount substantially higher than an amount equivalent to a stoichiometric conversion of the promoter agent to benzene carboxylic acid salt. The thusly formed benzene carboxylic acid salt is then recovered from the mixture or further processed into more valuable products such as by isomerization to terephthalic acid.